Apparatus for splitting a softenable film comprising bite rollers

ABSTRACT

Donor and receiver webs are advanced by a common drive mechanism from supply reels through a film splitting housing. The donor web carries a film layer having marking particles dispersed in depth in complementary imagewise configurations within the film layer. The webs and film layer are laminated at a bite mechanism inside the housing and the webs are separated as they leave the bite mechanism. The film layer is softened at the time of the lamination and separation and splits into separate layers adhering to each web. The split occurs between the complementary imagewise configurations of marking particles thereby yielding positive and negative images on the two webs.

United States Patent 1 Jones et al.

[111 3,770,554 Nov. 6, 1973 APPARATUS FOR SPLITTING A SOFTENABLE FILMCOMPRISING BITE ROLLERS 1 [73] Assignee: Xerox Corporation, Rochester,N.Y.

{22] Filed: July 6, 1971 [21] Appl. No.: 160,187

Related U.S. Application Data [63] Continuation of Ser. No. 875,136,Nov. 10, 1969,

abandoned.

|52 U.S. Cl. 156/510, 156/584 51 Int. Cl ..B32b 31/00 58 Field of Search156/584, 540, 254, 156/555, 510

[56] References Cited- UNITED STATES PATENTS 2,351,498 6/1944 Fowler156/254 2,511,703 6/1950 Ettl 156/555 3,132,040 5/1964 Messance...3,434,861 3/1969 Luc 156/254 Primary ExaminerDOuglas J. DrummondAtt0rneylames J. Ralabate et al.

[57] ABSTRACT Donor and receiver webs are advanced by a common drivemechanism from supply reels through a film splitting housing. The donorweb carries a film layer having marking particles dispersed in depth incomplementary imagewise configurations within the film layer. The websand film layer are laminated at a bite mechanism inside the housing andthe webs are separated as they leave the bite mechanism. The film layeris softened at the time of the lamination and separation and splits intoseparate layers adhering to each web. The split occurs between thecomplementary imagewise configurations of marking particles therebyyielding positive and negative images on the two webs.

28 Claims, 6 Drawing Figures llI-Illl PATENTEUxu-v 6 I975 3.770.554

SHEET 1 [IF 4 F/GZ 1 INVENTORS ILLIAM L. GOFFE 9R A JONES PATENTEnunvsum (BI-[70.554

SHEET 30F 4 APPARATUS FOR SPLITTING A SOFTENABLE FILM COMPRISING BITEROLLERS CROSS-REFERENCES TO RELATED APPLICATIONS This application is acont. of application Ser. No. 875,136 filed Nov. 10, 1969 now abandoned.

BACKGROUND OF THE INVENTION This invention relates to a novel imagingsystem in which marking particles are selectively moved through asoftenable layer under the influence of electrical forces. Specifically,this invention relates to apparatus for splitting a layer of softenablematerial that has previously experienced a migration of markingparticles to different depths or levels within it. Splitting thesoftenable layer separates the migrated and unmigrated particles intotwo separate layers which conventionally comprise positive and negativeimages.

Recently, a migration imaging system capable of producing high qualityimages of high density, continuous tone and high resolution has beendeveloped. Such migration imaging systems are disclosed in copendingapplications Ser. Nos. 837,780 and 837,591, filed June 30, 1969. Animaging member used in these new imaging systems is typically one ofthree configurations: (l) a layered configuration comprising asubstrate, a layer of softenable material and a fracturable andpreferably particulate layer comprising photosensitive material on orembedded at the upper surface of the softenable layer; (2) a binderstructure in which photosensitive particles are dispersed in asoftenable layer overcoating a substrate; or (3) an overcoated structurein which a layer comprising photosensitive particles is sandwichedbetween first and second layers of softenable material on a substrate.

Softenable as used herein is intended to mean any material which can berendered more permeable thereby enabling particles to migrate throughits bulk. Conventionally, changing permeability is accomplished by heator solvent softening. Fracturable layer of material as used herein andin the copending applications, means any particulate, continuous, orsemi-continuous layer of material which is capable of breaking up duringdevelopment, thereby permitting portions of said layer to migrate towardthe substrate or to be otherwise removed.

. A typical method of forming an image with one of the above describedimaging members is to form a latent electrostatic image on the surfaceof the imaging member followed by development of that image. One way toform the latent image is to uniformly charge a surface of the imagingmember and then expose it to a pattern of electromagnetic radiation suchas visible light. Most development methods include softening thesoftenable layer (hereafter referred to as the film layer) to allow thephotosensitive particles (generally the marking particles) to migratetoward the substrate thereby obtaining a distinct separation betweenexposed and non-exposed particles.

The present invention is concerned withsplitting a developed film layerwherein marking particles are already dispersed at different depths orlevelswithin the film. Copening application Ser. No. 784,164, filed Dec.16, 1968 sets forth various methods of dealing with developed filmsincluding splitting of the film to obtain positive and negative images.The present invention offers improvements over the splitting methodsdescribed in the copending applications by adding steps to the priormethods and by providing novel and efficient apparatus for performingthe splitting operation.

Accordingly, it is an object of the present invention to improve theabove identified particle migration imaging system. Specifically, it isan object of the present invention to devise novel means for efficientlyseparating a developed imaging member into layers bearing complementaryimages.

Another object of this invention is to devise apparatus for laminating afilm layer between donor and receiver webs and for separating the websto split the film layer.

Another object in keeping with the foregoing object is to deviseimproved means for uniformly dispensing the donor and receiver webs,with one web carrying the film layer to be split, for heating andcompressing the webs and film and for separating the webs.

Yet another object of the invention is to soften and split a film layerin a dark environment to prevent disturbances of the images at thedifferent levels in the film layer.

Still another object of the invention is to control the level at which afilm layer splits when it is subjected to opposed forces.

Even a further object of this invention is to devise means forsupporting, heating and rotating roller members for the compression andsplitting of film layers.

The above and other objects of the present invention are accomplished bynovel film splitting apparatus. The apparatus is designed to split afilm layer deposited on a donor web (the substrate for the softenablelayer) by heating or solvent softening the film, by compressing itbetween the donor web and a second or receiver web, forming a bondbetween the film and webs greater than the cohesive strength of thesoftened film, and by stripping the webs apart. One of the resultingsplit layers adheres to the donor web and the other to the receiver webyielding complementary images, i.e. a positive and a negative. The levelwithin the film at which separation or splitting occurs is varied bycontrolling the temperature gradient across the filmlayer. The webs areuniformly fed from supply reels by stripping means that includes acommon drive mechanism coupled to both web's. The webs are guided overinput rollers into bite means where they are compressed by smalldiameter bite rollers uniquely joumaled in supporting jaw mem bers. Thebite means is positioned inside a dark chamber. Heater elements insertedin the jaw members heat soften the film and a nozzle is available forsolvent softening. Input and output rollers are supported on either sideof the bite means in a manner that enables the angles between the websentering and exiting the bite means to be changed with the exit anglecontrolling the forces effecting the splitting of the film layer.

DESCRIPTION OF THE DRAWINGS Other objects and features of the presentinvention will be apparent from the present description and the drawingswhich are: 7

FIG. 1 is a front elevation view of the present film splittingapparatus;

FIG. 2 is a side elevation view of the film splitting apparatus;

FIG. 3 is a cross-sectional view of the film splitting apparatus takenalong lines 33 in FIG. 1;

FIG. 4 is an enlarged plan view of the bite means employed in the filmsplitting apparatus;

FIG. 5 is an enlarged side view of the bite means in FIG. 4; and

FIG. 6 is a schematic illustration of a film layer being split into twolayers having marking particles dispersed in complementary imagewiseconfigurations.

DESCRIPTION OF THE INVENTION The film splitter of the present inventionincludes the base 1, the back support 2, the housing 3, the stanchion 4,the hanger 5, the input rollers 7 and 8, the jaw members 9 and 10, theoutput rollers 12 and 13, the capstans 14 and 15 and the pressure gauge17.

The webs 18 and 19 are composed of, by way of example, transparentsynthetic materials such as that commercially available under the tradename Mylar". Web 18 is designated the donor web because it initiallycarries the film layer to be split. The donor web and the film layercomprises a developed imaging member as described earlier. The filmlayer is typically a softenable material that has previously beensoftened during a development process to disperse marking particles incomplementary imagewise configurations at different levels or depthswithin the film layer. The function of the film splitter is to sever thefilm layer at a level that separates the complementary images. The filmlayer is heat or solvent softened, sandwiched between the donor web andthe receiver web and split into one layer adhering to the donor web andanother layer adhering to the receiver web.

The foregoing operation is illustrated schematically in FIG. 6 wherein adonor web 40 carrying a developed film layer 41 is compressed against areceiver web 42 by bite rollers 43 and 44. The webs are laminated orcompressed together to establish an adhesive bond between the film andwebs that-is greater than the cohesive strength of the film at a levelwithin the film separating the marking particles 46 from markingparticles 47. Particles 46 and 47 are arranged at two distinct levels byearlier exposure and development steps not part of the presentinvention. The webs are stripped apart as they leave the bite rollerssevering the film into layer 48 adhering to the donor web and layer 49adhering to the receiver web.

In the present invention the film layer is maintained in a light freeenvironment by the housing 3 while it is softened to prevent the markingparticles from migrating as during development. Similarly, means areused in the present invention to dissipate or neutralize any residualelectric charge on the webs which might cause unwanted particlemigration when the film is softened. In this regard, corotron 51(FIG. 1) neutralizes charge by depositing charges on the donor web of apolarity opposite to that used in the development of the film layer.

Referring to FIG. 1, webs 18 and 19 are threaded through the splitterbetween the supply reels 20 and 21 and the fasteners 23 and 24 on thehanger. The webs pass through the apertures 25 and 26 into the darkchamber within the housing 3. The webs are guided by the input rollersto a point of contact at the bite rollers 28 and 29 mounted on the jawmembers. The webs are guided from the bite rollers by the outputrollers, are wrapped around the capstans and exit the housing viaapertures 30 and 31. The hanger travels upward on the stanchion touniformly advance the webs for the film splitting operation. The hangeris driven by the motor 35 coupled to the hanger by means of the cable 33carried on the pulleys 34 and 34a.

The housing 3 rests on the base 1 and has the back support 2 coupled toits rear wall. The back support provides means in which to mount thesupply reels 20 and 21. These reels are coupled to shafts on the dragbrakes 37 and 38 respectively and rotate to dispense the webs 18 and 19.The drag brakes are magnetic devices which oppose but do not prevent therotation of the reels and therefore help maintain a constant tension inthe webs as they are unwound.

The capstans 14 and 15 are positioned relative to the output rollers andthe output apertures 30 and 31 to allow the webs 18 and 19 to exit thehousing without physically contacting the roof of the housing. Likewise,the idler rollers 57 and 58 are positioned relative to the supply reelsand input rollers to permit the webs to enter the housing throughapertures 25 and 26 without physically contacting the walls of thehousing.

The splitting of asoftened film layer is accomplished as the webs 18 and19 are uniformly advanced past the bite rollers 28 and 29. The webs arewrapped over the output rollers and under the capstans to help separatethe webs as they leave the bite rollers. The forces effecting splittingare those forces aligned with the horizontal components of the webvelocities at the point where they leave the bite rollers. These forcescan be altered for a constant web speed by changing the angle 0 (FIG. 6)between the webs. To do this, the output rollers are rotatably mountedby appropriate means at one end of the pivotal members 52 and 53. Theother end of the pivotal members are coupled to the back support 2 bythe fasteners 54 and 55. The angle 0 is changed by merely loosening thefasteners 54 and 55 and rotating the pivotal members to a new location.The preferred magnitude for angle 0 varies with the thickness of thefilm layer, the speed of the web, the nature of the film material, thesoftness of the film, etc.

The input rollers 7 and 8 are supported in a manner that permits theangle B (FIG. 6) formed between the webs as they approach the biterollers to be varied. The input rollers 7 and 8 are joumaled forrotation by appropriate means in one end of the yokes 59 and 58. Theother end of the yokes are coupled to the undercarriages 62 and 63 byappropriate fasteners 64 and 65. The fasteners are loosened to changethe angle of the yokes relative to the undercarriages and thereby tochange the angle B. In addition, the angle B is varied by moving theundercarriages 62 and 63 toward or away from each other. Theundercarriages are slidably coupled by dovetails 84b (sloped matedsurfaces) with the slide support 84. Pinion gears 61 are journaled forrotation in the undercarriages and are mated with the rack gear 66extending the length of the slide support. (There is a hole in the slidesupport to permit the webs 18 and 19 to pass to the bite rollers.Consequently, rack gear 66 is in two parts with one being coupled to theslide support 84 on either side of the hole cut out for the webs.) Thepositions of the undercarriages are changed by rotating the pinion gears61. This is accomplished by inserting a screwdriver in a slot in theends of the shaft on which the pinion gears 61 are mounted. One effectthe angle B has on the splitting operation is to control the areaexposed to direct contact with solvent vapor issued through a nozzle 67positioned directly below the bite rollers. The angle B is also variedto make or avoid contact between the webs and the pre-heat elements 68and 69.

The pre-heat elements 68 and 69 are electrical heating rods insertedwithin appropriate holders. The holdcrs are made from materials that aregood conductors of heat and include hollow cylindrical posts 68b and69!) into which the heating rods are inserted. The cylindrical rollers68c and 690 are rotatably fit over the posts and rotate upon makingfriction contact with the webs. The pre-heat elements raise thetemperature of the webs and the film layer before they reach the biterollers. Heat is also conveyed to the film at the bite rollers tomaintain the film in a softened state or to increase the softenedcondition of the film. The electrical leads 71 and 72 couple thepre-heat elements to an appropriate electrical energy source.

The jaw members 9 and 10 and bite rollers 28 and 29 comprise the bitemeans for compressing the webs and film. The two jaw members includerespectively, the carriages 71 and 72, the heating blocks 73 and 74 andthe insulating blocks 76 and 77. The carriages (FIG. 2) are slidablycoupled to the slide support 84 by means of the dovetails 84a (matingsloped surfaces on the carriages and slide support.) The dovetailinterlocking of the carriages and the slide support stabilizes the biterollers 28 and 29 and prevents them from skewing or otherwise movingrelative to each other during the film splitting operation. In addition,the dovetail mounting permits the bite rollers to be repeatedlyseparated and returned to positions at which they are capable ofcontacting one another over substantially their entire length.

The carriages are also coupled to the slide support by means of rack andpinion gears. The rack gears 78 and 79 (FIG. 3) are fixedly coupled tothe slide supports and extend along its length. Each carriage has piniongears mated with the rack gears 78 and 79. The pinion gears 80 and 81coupled to carriage 71 (FIG. 3) are typical of like gears coupled tocarriage 72. The pinion gears are fastened to a shaft 83 which is inturn journaled for rotation in a carriage. A hole (mentioned earlier) iscut into the slide support between the rack gears 78 and 79 to permitthe webs l8 and 19 passage to the bite rollers.

The left hand carriage 71 has an adjustment mechanism coupled to itcomprising the knob 85 and threaded shaft 86. Thread on shaft 86 ismated with thread in the housing wall 87 and the right end of thethreaded shaft is rotatably coupled to the carriage 71. Consequently,the threaded shaft moves the carriage from left to right when the knobis rotated clockwise and moves the carriage from right to left when theknob is rotated counterclockwise. The adjustment mechanism is means forcontroll ably moving the left hand carriage 71 along the racks 78 and 79along'a collision path with the right hand carriage 72.

Carriage 71 is moved to the left when the webs l8 and 19 are beingthreaded through the film splitter and is moved to the right during thesplitting operation. The right hand carriage specifically the insulatingblock 77, collides with the pressure gauge 17 when it is moved to theright. The gauge is anchored against movement and typically has theright hand carriage 72 positioned in contact with it. When the left handcarriage 71 is moved to the right by the adjustment mechanism it forcesthe right hand carriage against the gauge 17. The gauge provides a readout of pressure exerted on the donor and receiver webs located betweenthe bite rollers 28 and 29. The compression pressure exerted on the filmis typically in the range of 3 to 15 pounds per square inch (psi).

The rack and pinion gears, the dovetail interlocking of parts andadjustment means provide positive control over the movement andpositioning of the bite rollers 28 and 29. The ability to closelycontrol and maintain the relative position or location of the biterollers provides precise and constant control over the forces exerted onthe webs 18 and 19 and the film layer between them.

The heating blocks 73 and 74 are coupled directly to the insulatingblocks 76 and 77 respectively and are made from a material that is agood conductor of heat. The insulating blocks 76 and 77 are mounteddirectly on the carriages 71 and 72 respectively and are made from amaterial that is a poor conductor of heat. Preferably, the insulatingblocks are made up of a plurality of laminated epoxy board. Theinsulating blocks confine the heat energy generated by the heat elements91 and 92 to the heating blocks and the bite rollers. The insulatingblocks add to the efficiency of the film splitting apparatus and enablethe carriages and other components to be handled without an operatorreceiving burns.

The heating elements 91 and 92 are substantially the same devices aselements 68 and 69 in that they are electrical heating rods of the typecommercially available under the trade name Watlow Firerod. Theelectrical leads 96 couple the heating elements to an appropriate energysource. The heating elements are inserted into cores or holes 89 and 90in the heating blocks. The heat energy generated by the heating elementsis transmitted to the bite rollers and then to the film layers primarilyby conduction through the body of the heating blocks. The heat energyproduced by the heating elements is selected to be sufficient to lowerthe cohesive strenth of a film layer below the levels of the adhesivebonds between the film and the donor and receiver webs.

It has been found that the depth or level at which the film layer splitscan be varied by changing the heat gradient across the film, e.g.heating one side of the film to a higher temperature than the otherside. This is accomplished by varying the electrical current flow to theheating elements 91 and 92 such that the temperature of one is greaterthan the other. Alternatively, one of the heating elements may becompletely removed from the heating block. The film tends to split at alevel closer to the web at the higher temperature. To repeat, thefilm'tends to split at a level relative to the center of the film thatis adjacent the web at the higher temperature. The heat energy istransmitted to the film layer through the donor and receiver webs.Consequently, the temperature of the webs establishes the gradientacross the film layer. it is possible therefore to employ the pre-heatelements 68 and 69, the solvent nozzle 67 and the heating elements 91and 92 in a variety of ways to effect some particular heat gradientacross the film layer. If only vapor softening is used splitting occurson the average in the center of the film. The speed of the webs is alsoa factor to be considered since both heat and solvent softening aredependent upon the length of time to which the film is exposed tosolvent or heat.

The bite rollers 28 and 29 are mounted on the narrow or pointed ends ofthe heating blocks and their peripheries are the surfaces at which thejaw members collide. The bite rollers are joumaled for rotation by meansthat include the journal blocks 94 and 95 coupled by appropriate meansto the heating blocks 73 and 74 respectively. The journal blocks haveV-shaped grooves extending their width and in which the bite rollers arerotatably seated. The bite rollers are supported over most of theirlength by the journal blocks to prevent buckling or bowing of the biterollerswhen subjected to the web compressing pressures. There aregrooves at each end of a bite roller in which a turn or loop of a coilspring 93 is rotatably fit. The loops or turns 97 (4 total) act as athrust bearing for the roller while each spring (4 total) is anchored toa heating block to act as a bias mechanism for holding or seating thebite rollers firmly in the V-grooves of the journal blocks. The V-shapedor tapered grooves are selected to permit the journal blocks to seatdifferent diameter bite rollers and to minimize the friction surfacecontact with a bite roller while providing support against bending orother deformation. The V-shape groove is also selected because it iseasily manufactured even for small diameter rollers.

The v grooves of the joumal'blocks 94 and 95 are preferably coated witha low friction material such as Teflon to improve the ability of thebite rollers to rotate upon making friction contact with a moving web.Also, the journal blocks are typically made of a material that is a goodconductor of heat. Although materials such as Teflon are relatively poorconductors of heat, heat is still efficiently conveyed to the biterollers because the Teflon (or other low friction material) coating isrelatively thin so as not to form a significant heat barrier between'thebite rollers and their journal blocks.

The diameter of a bite roller is generally in the order of from aboutl/32 inch to about one-half inch. The presently preferred diameter sizeis one-eighth inch. This small diameter is purposefully selected tominimize the effect of dirt, dust, and other foreign objects on theperiphery of the bite rollers, on the webs and on the film. lf foreignobjects are on the rollers, webs or film they create faults in theimages and otherwise adversely affect the splitting of the film layer.The foreign objects alter the adhesive contact and distribution offorces between web and film and are unwanted discontinuities in the filmand web sandwich structure. The closed housing 3 affords additionalprotection against dirt, dust and other foreign objects. Also, thejournal blocks 94 and 95 contact a bite roller over its length and actto clean the surface of a roller as it rotates.

The small diameter bite rollers are also advantageous because theyminimize the area on the film and webs to which a force is applied.Consequently, the presently preferred compression pressures of 3 to psiare attainable with the exertion of a relatively small force between thebite rollers. Furthermore, the small diameter of the bite rollerspermits a more rapid separation of the webs. The rapid web separationminimizes the formation and size of film strands stretching between thewebs after leaving the bite rollers. On the other hand, the small rollerdiameters create the practical problems of having sufficient structuralstrength to resist bowing or bending under the compression pressures andof having bearings that allow the bite rollers to freely rotate uponmaking friction contact with a moving web,

or alternatively, to being motor driven. These problems are overcome bythe presently used apparatus for journaling and supporting the biterollers.

Appropriate plumbing is coupled to the nozzle 67 for pumping the solvent(normally a gas) from a supply reservoir and for directing it onto thewebs. Nozzle 67 consists of a pipe substantially the same length of thebite rollers having a plurality of holes drilled in the line along itslength. The holes are oriented relative to the bite rollers to directthe solvent to the nip between the bite rollers. The solvent vaporapparatus is provided principally as an alternate means for filmsoftening but may also be used jointly with the heat softeningapparatus, i.e. heating elements 68, 69, 91 and 92.

In operation, supply reels 20 and 21 are mounted onto the shafts of thedrag brakes 37 and 38. The donor web 18 is pulled from reel 20 andthreaded through the machine to the fastener 23 on hanger 5. Likewise,the receiver web 19 is pulled from reel 21 and threaded through themachine to fastener 24. The hanger is initially located at its lowermostposition on the stanchion 4. The left jaw member is moved to the left toprovide space between the bite rollers for the threading operation. Oncethe webs are threaded, the adjustment means is used to compress the websbetween the bite rollers. A leader is often coupled to each web tofacilitate the threading of the webs and to afford them some degree ofprotection. A front panel (not shown) is removed from the housing toallow the operator access to the various rollers in order to thread thewebs. Before the front panel is replaced, the pressure exerted on thewebs is monitored on the readout scale of the pressure gauge 17. Thepressure is of course adjusted to some predetermined level by means ofthe adjustment knob and shaft 86. With this done, the front panel ismounted on the housing thereby shielding the film and webs from light.The closed housing defines a dark chamber in which the splittingoperation takes place.

Conventionally, the heating elements 91 and 92 are energized at a muchearlier time to allow the heating blocks to reach predeterminedoperating temperatures. Likewise, the pre-heat elements 68 and 69 areenergized at an earlier time to bring the holders supporting them to adesired operating temperature.

Next, the electric motor 35 is energized propelling the hanger upward onthe stanchion. The webs are unwound from the supply reels at uniformrates because, for one, they are coupled to a common drive mechanism. Ifsolvent softening is being used, a gas solvent is directed from nozzle67 onto the moving web. The webs are heated as they travel past thepre-heat elements 68 and 69 and again when they are in the nip betweenthe bite rollers. The softened film is compressed between the websforming a strong adhesive bond with each web. Immediately after the webspass the bite rollers they separate toward the output rollers. Theforces at separation split the film layer substantially down the middle.(The location of the split may be shifted right or left of center byappropriate heat gradients as explained earlier.) Typically, the film,now on both webs, hardens by the time it passes over the output rollers12 and 13 and clearly before it comes into contact with the capstans 14and 15. The hardened film layers may once again be softened by heat orsolvent after the webs pass the capstans. (Heating elements 98 and 99are illustrative apparatus). This subsequent softening of the split filmlayers smooths out ragged surfaces of the film and permits randomlydislocated marking particles to move closer to the webs.

Finally, the webs exit the housing and are available for immediatevisual inspection. The height of the stanchion 4 is sufficient for thehanger to advance the webs from a position below the bite rollers to aposition well outside the housing. At this point in time, the splittingoperation may be continued by: severing the webs at a point just outsidethe exit apertures 30 and 31; lowering the hanger to its startingposition; coupling the threaded webs extending from the housing tofasteners 23 and 24, and; energizing the electric motor 35.

What is claimed is:

l. A bite roller apparatus comprising:

first and second opposed, axially parallel bite rollers having diametersin the range from about 1/32 inch to about one-half inch;

first and second journal blocks, said first and second bite rollers eachrotatably peripherally supported I along substantially the entire axiallength of the pressure bearing portion of said roller in a groove ineach of said first and second journal blocks, respectively;

means for advancing at the same speed a first web and a second web, eachrespectively contacting an opposite surface of a softenable film,between said first and second bite rollers; and

means for separating the webs exiting from said bite rollers whereby thesoftenable film may be split leaving a first thin softenable film onsaid first web and leaving a second thin softenable film on said secondweb.

2. The apparatus of claim 1 additionally comprising means for applying asoftening medium to said softenable film.

3. The apparatus of claim 2 wherein said medium applying means comprisesmeans for applying a solvent to said softenable film to soften said filmprior to advancing said film and webs between said bite rollers.

4. The apparatus of claim 2 wherein said medium applying means comprisesmeans for heating said softenable film to soften said film prior toadvancing said film and webs between said bite rollers.

5. The apparatus of claim 4 wherein said means for heating comprisesfirst and second means for heating, said first and second means forheating, respectively, located contiguous the paths of said first andsecond webs, to heat said webs prior to advancing said webs between saidbite rollers.

6. The apparatus of claim 2 wherein the means for advancing said websbetween said bite rollers is a single drive means capable of beingdirectly coupled to each web.

7. The apparatus of claim 6 wherein said single drive means includes ahanger for coupling directly to said webs, said hanger being supportedfor travel along a linear path.

8. The apparatus of claim 7 additionally comprising first and secondoutput rollers and first and second capstans between said hanger andsaid first and second bite rollers, for separating said webs exitingsaid bite rollers.

9. The apparatus of claim 8 additionally comprising means for varyingthe position of the output rollers relative to the bite rollers forvarying the angle of separation between the webs exiting the biterollers.

10. The apparatus of claim 1 additionally comprising means for applyinga softening medium to at least one of said thin soft-enable filmsthereby smoothing the free surface of said thin film after said websexit said bite rollers and are separated, said means for softening beingcontiguous the path of at least one of said webs.

l 1. The apparatus of claim 10 wherein said means for applying asoftening medium comprises a first and second means for applying asoftening medium for softening said thin softenable films, said firstand second means for applying a softening medium, respectively,contiguous the paths of said first and second webs, to smooth the freesurfaces of said thin softenable films.

12. The apparatus of claim 10 wherein said means for applying asoftening medium comprises means for heating said thin softenable film.

13. The apparatus of claim 10 wherein said means for applying asoftening medium comprises means for applying a solvent for said thinsoftenable film to said film.

14. The apparatus of claim 2 additionally comprising a first supply reelhaving said first web wound thereon, and a second supply reel havingsaid second web wound thereon.

15. The apparatus of claim l4 additionally comprising drag means coupledto said supply reels for applying tension to said webs as they areadvanced through said apparatus.

16. The apparatus of claim 14 additionally comprising first and secondinput rollers positioned between said first and second supply reels andsaid first and second bite rollers, respectively, for varying the anglebetween said webs as said webs approach said bite rollers.

17. The apparatus of claim 16 additionally comprising means for applyinga solvent to said softenable film, said means for applying positioned todirect said solvent into the angle between said webs, and wherein saidsoftenable film is located on the surface of one of said webs, saidsurface within the angle between said webs into which said solvent isdirected.

18. A bite roller apparatus comprising:

first and second opposed, axially parallel bite rollers having diametersin the range from about 1/32 inch to about one-half inch;

first and second journal blocks, said first and second bite rollers eachrotatably peripherially supported along substantially the entire axiallength of the pressure bearing portion of said roller in a groove ineach of said first and second journal blocks, respectively;

a supporting slide member; and

means for supporting said journal blocks including dove-tail couplingbetween said means for supporting said journal blocks and saidsupporting slide member.

19. Apparatus for splitting a softenable film between a pair of webscontacting the opposite surfaces of said film, said film containing atleast two images of migration marking material, said images at least inpart spaced apart across the thickness of said softenable I means forapplying a softening medium to said softenable film; and

means for advancing at the same speed said webs, be-

tween said first and second bite rollers, and means for separating thewebs exiting from said bite rollers thereby splitting said softenablefilm leaving a first thin softenable film containing one image on oneweb and a second thin softenable film containing another image on theother web.

20. The apparatus of claim 19 wherein said means for applying asoftening medium comprises means external to said bite rollers forheating said bite rollers, said heating means coupled to said journalblocks.

21. The apparatus of claim 19 wherein said means for applying asoftening medium comprises means for applying a solvent for saidsoftenable film to said film prior to advancing said film and websbetween said bite rollers.

22. The apparatus of claim 19 wherein said means for advancing said webscomprises a single drive means capable of being directly coupled to eachweb.

23. The apparatus of claim 19 wherein the softenable film to be split islocated on the surfaces of one of said webs, and said apparatusadditionally comprises means for electrically discharging said web andfilm before advancing said film past the means for applying a softeningmedium and said bite rollers, said means for discharging locatedcontiguous the path of said web which supports said softenable film tobe split.

24. The apparatus of claim 19 additionally comprising a dark chamberenclosing at least said bite rollers,

said dark chamber for preventing light from impinging upon saidsoftenable film while said film is in its softened condition.

25. Apparatus for splitting a softenable film of thickness in the rangefrom about one-half micron to about 16 microns between a pair of webscontacting the opposite surfaces of said film, said film containing atleast two images of migration marking material, one of said imagescontiguous one surface of said film, and another image contiguous theother surface of said film, and said migration marking materialcomprising particulate material of average particle size in the rangefrom about 0.1 microns to about 2 microns, said apparatus comprising: 7

first and second opposed, axially parallel bite rollers having diametersin the range from about 1/32 inch to about one-half inch, and first andsecond journal blocks, said first and second bite rollers each rotatablyperipherially supported along substantially the entire axial length ofthe pressure bearing portion of said roller in a groove in each of saidfirst and second journal blocks, respectively, and said rollers coupledwith said journal blocks by means including bias springs coupled betweeneach bite roller and its respective journal block,

means for applying a softening medium to said softenable film; and

a single drive means capable of being directly coupled to each web foradvancing said webs at the same speed between said first and second biterollers, and means for separating the webs exiting from said biterollers thereby splitting said softenable film leaving a first thinsoftenable film containing one image of migration marking material onone web and a second thin film of migration marking material containinganother image of migration marking material on the other web.

26. The apparatus of claim 25 wherein said means for applying asoftening medium to said softenable film comprises means external tosaid bite rollers for heating at least one of said bite rollers, saidheating means coupled to the respective journal block wherein said onebite roller is supported, said heating means capable of heating at leastsaid one bite roller by conduction through said journal block.

27. The apparatus of claim 26 comprising means external to said biterollers for heating said bite rollers, said heating means coupled tosaid journal blocks and capable of heating said bite rollers byconduction through said journal blocks.

28. The apparatus of claim 25 wherein said means for applying asoftening medium to said softenable film comprises means for applying asolvent for said softenable film to said film prior to advancing saidwebs between said bite rollers.

1. A bite roller apparatus comprising: first and second opposed, axiallyparallel bite rollers having diameters in the range from about 1/32 inchto about one-half inch; first and second journal blocks, said first andsecond bite rollers each rotatably peripherally supported alongsubstantially the entire axial length of the pressure bearing portion ofsaid roller in a groove in each of said first and second journal blocks,respectively; means for advancing at the same speed a first web and asecond web, each respectively contacting an opposite surface of asoftenable film, between said first and second bite rollers; and meansfor separating the webs exiting from said bite rollers whereby thesoftenable film may be split leaving a first thin softenable film onsaid first web and leaving a second thin softenable film on said secondweb.
 2. The apparatus of claim 1 additionally comprising means forapplying a softening medium to said softenable film.
 3. The apparatus ofclaim 2 wherein said medium applying means comprises means for applyinga solvent to said softenable film to soften said film prior to advancingsaid film and webs between said bite rollers.
 4. The apparatus of claim2 wherein said medium applying means comprises means for heating saidsoftenable film to soften said film prior to advancing said film andwebs between said bite rollers.
 5. The apparatus of claim 4 wherein saidmeans for heating comprises first and second means for heating, saidfirst and second means for heating, respectively, located contiguous thepaths of said first and second webs, to heat said webs prior toadvancing said webs between said bite rollers.
 6. The apparatus of claim2 wherein the means for advancing said webs between said bite rollers isa single drive means capable of being directly coupled to each web. 7.The apparatus of claim 6 wherein said single drive means includes ahanger for coupling directly to said webs, said hanger being supportedfor travel along a linear path.
 8. The apparatus of claim 7 additionallycomprising First and second output rollers and first and second capstansbetween said hanger and said first and second bite rollers, forseparating said webs exiting said bite rollers.
 9. The apparatus ofclaim 8 additionally comprising means for varying the position of theoutput rollers relative to the bite rollers for varying the angle ofseparation between the webs exiting the bite rollers.
 10. The apparatusof claim 1 additionally comprising means for applying a softening mediumto at least one of said thin soft-enable films thereby smoothing thefree surface of said thin film after said webs exit said bite rollersand are separated, said means for softening being contiguous the path ofat least one of said webs.
 11. The apparatus of claim 10 wherein saidmeans for applying a softening medium comprises a first and second meansfor applying a softening medium for softening said thin softenablefilms, said first and second means for applying a softening medium,respectively, contiguous the paths of said first and second webs, tosmooth the free surfaces of said thin softenable films.
 12. Theapparatus of claim 10 wherein said means for applying a softening mediumcomprises means for heating said thin softenable film.
 13. The apparatusof claim 10 wherein said means for applying a softening medium comprisesmeans for applying a solvent for said thin softenable film to said film.14. The apparatus of claim 2 additionally comprising a first supply reelhaving said first web wound thereon, and a second supply reel havingsaid second web wound thereon.
 15. The apparatus of claim 14additionally comprising drag means coupled to said supply reels forapplying tension to said webs as they are advanced through saidapparatus.
 16. The apparatus of claim 14 additionally comprising firstand second input rollers positioned between said first and second supplyreels and said first and second bite rollers, respectively, for varyingthe angle between said webs as said webs approach said bite rollers. 17.The apparatus of claim 16 additionally comprising means for applying asolvent to said softenable film, said means for applying positioned todirect said solvent into the angle between said webs, and wherein saidsoftenable film is located on the surface of one of said webs, saidsurface within the angle between said webs into which said solvent isdirected.
 18. A bite roller apparatus comprising: first and secondopposed, axially parallel bite rollers having diameters in the rangefrom about 1/32 inch to about one-half inch; first and second journalblocks, said first and second bite rollers each rotatably peripheriallysupported along substantially the entire axial length of the pressurebearing portion of said roller in a groove in each of said first andsecond journal blocks, respectively; a supporting slide member; andmeans for supporting said journal blocks including dove-tail couplingbetween said means for supporting said journal blocks and saidsupporting slide member.
 19. Apparatus for splitting a softenable filmbetween a pair of webs contacting the opposite surfaces of said film,said film containing at least two images of migration marking material,said images at least in part spaced apart across the thickness of saidsoftenable film, said apparatus comprising: first and second opposed,axially parallel bite rollers having diameters in the range from about1/32 inch to about one-half inch, and first and second journal blocks,said first and second bite rollers each rotatably peripherally supportedalong substantially the entire axial length of the pressure bearingportion of said roller in a groove in each of said first and secondjournal blocks, respectively; means for applying a softening medium tosaid softenable film; and means for advancing at the same speed saidwebs, between said first and second bite rollers, and means forseparating the webs exiting from said bite rollers thereby splittingsaid softenaBle film leaving a first thin softenable film containing oneimage on one web and a second thin softenable film containing anotherimage on the other web.
 20. The apparatus of claim 19 wherein said meansfor applying a softening medium comprises means external to said biterollers for heating said bite rollers, said heating means coupled tosaid journal blocks.
 21. The apparatus of claim 19 wherein said meansfor applying a softening medium comprises means for applying a solventfor said softenable film to said film prior to advancing said film andwebs between said bite rollers.
 22. The apparatus of claim 19 whereinsaid means for advancing said webs comprises a single drive meanscapable of being directly coupled to each web.
 23. The apparatus ofclaim 19 wherein the softenable film to be split is located on thesurfaces of one of said webs, and said apparatus additionally comprisesmeans for electrically discharging said web and film before advancingsaid film past the means for applying a softening medium and said biterollers, said means for discharging located contiguous the path of saidweb which supports said softenable film to be split.
 24. The apparatusof claim 19 additionally comprising a dark chamber enclosing at leastsaid bite rollers, said dark chamber for preventing light from impingingupon said softenable film while said film is in its softened condition.25. Apparatus for splitting a softenable film of thickness in the rangefrom about one-half micron to about 16 microns between a pair of webscontacting the opposite surfaces of said film, said film containing atleast two images of migration marking material, one of said imagescontiguous one surface of said film, and another image contiguous theother surface of said film, and said migration marking materialcomprising particulate material of average particle size in the rangefrom about 0.1 microns to about 2 microns, said apparatus comprising:first and second opposed, axially parallel bite rollers having diametersin the range from about 1/32 inch to about one-half inch, and first andsecond journal blocks, said first and second bite rollers each rotatablyperipherially supported along substantially the entire axial length ofthe pressure bearing portion of said roller in a groove in each of saidfirst and second journal blocks, respectively, and said rollers coupledwith said journal blocks by means including bias springs coupled betweeneach bite roller and its respective journal block, means for applying asoftening medium to said softenable film; and a single drive meanscapable of being directly coupled to each web for advancing said webs atthe same speed between said first and second bite rollers, and means forseparating the webs exiting from said bite rollers thereby splittingsaid softenable film leaving a first thin softenable film containing oneimage of migration marking material on one web and a second thin film ofmigration marking material containing another image of migration markingmaterial on the other web.
 26. The apparatus of claim 25 wherein saidmeans for applying a softening medium to said softenable film comprisesmeans external to said bite rollers for heating at least one of saidbite rollers, said heating means coupled to the respective journal blockwherein said one bite roller is supported, said heating means capable ofheating at least said one bite roller by conduction through said journalblock.
 27. The apparatus of claim 26 comprising means external to saidbite rollers for heating said bite rollers, said heating means coupledto said journal blocks and capable of heating said bite rollers byconduction through said journal blocks.
 28. The apparatus of claim 25wherein said means for applying a softening medium to said softenablefilm comprises means for applying a solvent for said softenable film tosaid film prior to advancing said webs between said bite rollers.